The present invention relates to scaffolding equipment in general, and more particularly to upright poles utilized with pump jacks traveling up and down thereupon.
It has been customary in various industries, for example, while working on exteriors of houses, to erect scaffolding in order to permit workers to stand at an elevation above ground surface. Typically, scaffolding systems are utilized in installations of aluminum or vinyl siding. Such scaffolding systems utilize pump jack poles which are laterally spaced from each other and secured to the house by a brace. Pump jacks, which include support arms for supporting a scaffolding staging, and also include shackles which clamp onto the upright poles, are used to travel up and down the poles. Workers stand on the scaffolding staging and operate the pump jack by means of a foot pump to thereby move the staging up and down along the upright poles.
An improved pole used for pump jacks is described in my U.S. Pat. No. 4,382,488. Such poles are formed of metal tubing and have a rubberized surface provided on one side of the metal pole. The metal pole is preferably of rectangular cross-section and the rubberized material is secured to the face of the metal poles by adhesive and/or rivets. Securement of the rubberized material to the metal wall of the tubular pole must be reliable to support the weight of a worker when he stands on the staging with the shackles of the pump jack gripping the pole. In the aforementioned patent, it was shown that although the shackles of the pump jack clamps the pole on two opposing sides, only one of these need be covered by rubber to still provide adequate gripping of the pole and support the weight of workers on the scaffolding staging.
Due to substantial transmittal forces acting on the rubberized material when the worker's weight is applied to the staging, the adhesive connection between the rubberized strip and the metal pole must be secure. Using rivets in addition to the adhesive connection between the rubberized material and the metal wall of the pole improves the connection between the rubber and the metal pole. However, using rivets increases labor costs as well as material expenses in producing pump jack poles. Furthermore, should a submerged surface become damaged, it is not feasible to replace the rubberized section without the need for expensive equipment, time and cost.
Accordingly, there has been need to provide a secure connection between the rubberized surface and the metal pole and yet provide such securement with less expensive means than that of the prior art poles.